Japanese Unexamined Patent Application Publication No. 2004-268903 discloses an airbag for receiving a passenger at the time of a vehicle collision and a folding method thereof. The airbag has a left airbag section and a right airbag section that are inflated on the right and left, respectively, in front of a passenger, and adapted to be inflated by an inflator common to the airbag sections. In the airbag disclosed in the publication, the left airbag section and the right airbag section are not connected to each other at their leading ends, and longitudinal middle portions of the airbag sections are connected by a connecting part.
In the above publication, portions of the airbag sections closer to the leading ends than the connecting part are folded along vertical folding lines, respectively, so as to be primary folded bodies. Then, the primary folded bodies are folded to be smaller.
This airbag is folded and accommodated within a case and covered with a cover. When the inflator (gas generator) begins to discharge gas at the time of a vehicle collision, the airbag is inflated toward the front of a passenger while pushing the cover open.